refactor: Deprecation messages for old style array mapping

src/Recyclarr.TrashLib/Config/Parsing/ConfigDeprecations.cs

@@ -0,0 +1,18 @@
+using YamlDotNet.Core;
+
+namespace Recyclarr.TrashLib.Config.Parsing;
+
+public static class ConfigDeprecations
+{
+    public static string? GetContextualErrorFromException(YamlException e)
+    {
+        if (e.Message.Contains("Expected 'MappingStart', got 'SequenceStart'"))
+        {
+            return "Found array-style list of instances instead of named-style. " +
+                "Array-style lists of Sonarr/Radarr instances are not supported. " +
+                "See: https://recyclarr.dev/wiki/upgrade-guide/v5.0/#instances-must-now-be-named";
+        }
+
+        return null;
+    }
+}

src/Recyclarr.TrashLib/Config/Parsing/ConfigParser.cs

@@ -58,6 +58,8 @@ public class ConfigParser
         }
         catch (YamlException e)
         {
+            _log.Debug(e, "Exception while parsing config file");
+
             var line = e.Start.Line;
             switch (e.InnerException)
             {
@@ -67,7 +69,11 @@ public class ConfigParser
                     break;
 
                 default:
-                    _log.Error("Exception at line {Line}: {Msg}", line, e.InnerException?.Message ?? e.Message);
+                    // Check for Configuration-specific deprecation messages
+                    var msg = ConfigDeprecations.GetContextualErrorFromException(e) ??
+                        e.InnerException?.Message ?? e.Message;
+
+                    _log.Error("Exception at line {Line}: {Msg}", line, msg);
                     break;
             }